SWAN VALLEY, Idaho — Concerned that a dry winter could yield too little water to adequately support late-season power generation, the Bureau of Reclamation has decreased flows below Palisades Reservoir.

The decision to reduce flows from 1,200 cubic feet per second to 900 cfs, effective Jan. 5, was welcome news to many Upper Snake River irrigation managers, who had repeatedly requested such a change to preserve future water delivery options.

Roland Springer, manager of reclamations with the bureau’s Upper Snake Field Office, explained other irrigators in the Magic Valley supported 1,200 cfs flows as a means of maximizing winter power production and limiting their pumping costs.

Electricity marketed by Bonneville Power Administration from the bureau’s 176-megawatt Palisades hydropower plant helps the agency defray reservoir management costs, and the savings is passed on to storage holders. During the irrigation season, releases typically exceed the capacity of the turbines, leading to a lost opportunity to produce power.

In defense of maintaining 1,200 cfs flows until now, Springer said there’s ample storage space downstream in American Falls Reservoir, which is 59 percent full. He said models show there’s little chance that American Falls will fill and lead to wasted water to free more storage space. American Falls was built earlier than Palisades and has a senior priority date, but a large volume of American Falls storage rights are kept in Palisades for greater flexibility.

The Upper Snake snowpack is now at about 92 percent of normal, and Palisades is 24 percent full. Though Springer said there’s little chance that Palisades will drain low enough to impair power production, he said the bureau ultimately agreed to the reduction to ensure it can meet its regional power requirements late in the season. He said 900 cfs is the minimum amount required to protect fish populations.

“We know it’s a drought year and we know we have to conserve water, and we’re doing that,” Springer said, adding irrigation is the bureau’s top priority.

Springer said the bureau began hearing concerns from irrigators about the 1,200 cfs flows in November and shared its logic and analysis with them at an annual meeting during the second week of December. He said some members of the Committee of Nine, an oversight committee representing irrigation interests in Water District 1, requested decreased flows.

Lyle Swank, watermaster over Water District 1, said he, too, encouraged a reduction in flows to retain sufficient upstream water for deliveries.

“Even if American Falls isn’t clear full, you still may want to have water upstream to run through canals between American Falls and Palisades,” Swank said. “Sometimes it’s just good to be able to preserve your options.”

Steve Howser, general manager of Aberdeen-Springfield Canal Co., said 900 cfs is the “most I would feel comfortable with in a drought year like this.”

“It makes more sense to keep storage water as high in the system as possible,” Howser said. “That means storing American Falls water in Palisades until the end of the season.”